How to Build a Real Igloo | Hacker News Reader

How to Build a Real Igloo

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79 pointsvishnuharidas30 comments

The kind of structure you build depends a lot on the snow conditions where you are building it. I don't spend a lot of time where the snow is stiff enough to make an igloo (unless I use an igloo tool, which is fun as a novelty but not something I want to drag around on a backpacking trip). Instead I like to make a structure from the softer, denser snow of the sierras, using a technique closer to carving out a cave.

Making a structure at all depends a lot on your plans. It takes time, but is worth it if you're going to spend a couple of days in one place, especially if there's a storm coming in (that you were foolish enough not to plan for, cough). If you're traveling, it's often easier to simply sleep out in the open (I dig a shallow trench about 500 mm deep to avoid convection cooling overnight). This probably sounds crazy but once you do it you'll find you sleep fine. I learned it on a camping trip in Minnesota where the overnight temps were below 0 Fahrenheit. I was quite dubious at first but my friends insisted it would be fine and they were right!

If you look at the Nanook of the North video, you'll see they make pretty solid and large igloos and then move into them for extended periods. In that case it's worth the time it takes to get the job done really well.

I teach my students to make emergency shelters in ways that are quick and temporary, using whatever is at hand (branches, skis, random tree wells, etc). If it's an emergency, you presumably don't have the time to making anything fancy. (I only once ever heard of a former student actually doing this).

Sadly, climate change has made the snow conditions in most of the sierras unsuitable for making shelters for the past few seasons.

> If you're traveling, it's often easier to simply sleep out in the open

Note that you need a really good sleeping bag for this to work, don't sleep outside in the snow if you don't have a sleeping bag rated for extremely low temperatures. It isn't uncommon for people to die when hiking in winter landscapes, so don't underestimate it.

Yes! Note that there is no official system for determining if a sleeping bag is a "20 degree" or "minus 15 degree" -- the manufacturers can write what they want. But almost anywhere in the sierras a decent down bag is perfectly adequate.

But you need a whole sleep system: I use a couple of closed cell pads and a tarp in addition to my bag. In much colder conditions you need a couple of bags. There's a lot to learn on this topic: site selection, how to dress at night, how to keep your boots from freezing overnight...

Note that when I said "traveling" I mean on skis and/or snowshoes. If you are in a car and it breaks down DON'T LEAVE YOUR VEHICLE.

I have only used an emergency shelter once (a consequence of poor planning on my part). My dog and I spent a relatively cold night sitting on pads and wrapped together in our bags. I made sure I did not fall asleep. Winter nights are long. I never want to do that again.

How does a trench avoid convection cooling?

I'd imagine the air around your body doesn't move as much because it's somewhat sheltered from the wind

Yes, you have some radiative cooling downward and upward but you get a little static boundary layer above you instead of convective flow. You can do the same by making a little wall the same size (you have to do this when sleeping on the ice -- don't attempt that in california!) but I find digging a little trench easier. The same effect either way.

Thanks - BTW I was confused because I'd call that avoiding "wind-chill", or even avoiding "advection cooling" (from a techincal fluid dynamics perspective)... "convection cooling" makes me think of heat loss by warmer air rising, not due to lateral flow. But that's the ordinary meaning - technically, convection and advection are synonyms, so you're quite right.

I am now fascinated by how those people can cut ice at the right angle to not have it fall on them... they are interlocking, and sure, its ice/snow, but with no measurements, by hand, just eying it. That is pretty impressive.

You cut adjustments as you place the blocks, a saw slides right through blocks of snow so it is easier than it looks. I haven't made such a large igloo, but getting the blocks cut right isn't the hard part.

The material might actually help. I'm guessing that as you slide the blocks against each-other, friction melts the surfaces. When the blocks settle, the surfaces re-freeze, gluing them together.

They pack the gaps with snow and the blocks are cut on an angle so they are larger on the outside than the inside. Also, igloos aren't built out of ice. It's compacted snow. Much easier to work with.

One trick is to make sure the cut lines are such that they all point to a single point in the center of the igloo.

Also they butt the blocks first, then make the cut, so the surfaces mate perfectly.

My attempt, though out of ice, not snow: https://photos.app.goo.gl/HVhou8xPGGG21toj9

The upside is that you can light it up!

https://photos.app.goo.gl/kpVoVAEqGgE6RjGB6

Incidentally, damn does your house resemble the Amityville Horror home.

Nanook of the North's depiction:

https://www.youtube.com/watch?v=3F0G3IZA6OI

Matthias Wandel's take:

https://www.sentex.ca/~mwandel/winter/igloo.html

https://www.sentex.ca/~mwandel/winter/igloo2.html

I used to go igloo camping with my scout troop every winter so I’ve had lots of experience building igloos and a-frames. If it’s just 1-2 people an a-frame is much simpler and quicker to build, although a snow cave can be even faster if the conditions are right for it. Depending on how deep you dig an igloo will fit 3-5 people and can be expanded with multiple a-frames if you have even more. The more people you can cram in, the warmer it is.

A few years ago I went on an 3-day snowshoe trip with a couple of friends in Montana. On the second day it was significantly colder than the first and one of my friends had been complaining about being cold at night. Luckily our other friend had packed a portable snow saw so we decided to stop early and build an igloo. We lucked out and the snow was in good condition so we didn’t have to prepare it first. If the snow is too dry and powdery you first have to stomp down a large area with snowshoes and then wait an hour or so for it to harden before you can cut good blocks from it. If I remember correctly it took us about 4 hours to build a decent size igloo and shovel it out. It’s amazing how warm they can get inside. It was about 0°F outside that night not including windchill, but inside it was warm enough that I needed to unzip my sleeping bag a bit.

If you get the chance to build an igloo and sleep in it, I highly highly recommend it. It’s super fun and is something you will remember forever. Bring a tent as backup unless you already have experience :)

I’ve only once built a reasonable igloo in the manner depicted in the video. It requires dry snow having a consistency a bit like styrofoam. Snow caves in a big snowdrift or under the branches of a large snow covered fir tree are much more likely to be practical shelters. (Be careful not to warm up the cave under snow covered branches too much or the roof of you cave can collapse and melt.

I live in Texas now so there isn’t as much opportunity to make use of these skills. Buffalo, on the other hand had plenty of snow.

I did this in a field in Hirafu Village, Japan[1] near the end of April about 8 years ago . We didn't know about the spiral part, and so we just did it in layers. The spiral approach does seem like it would add a whole lot more stability that was hard to get without the first two bricks in each layer being a bit precarious. Our tools were mainly an avalanche shovel and a few snowboards.

When it was done, we managed to fit about 11-12 people inside, and had a small fire on a table fashioned in the middle of the igloo (as well as way too much Saki). If you ever get a chance to do this, it's tough work, but well worth it.

[1]: Somewhere around 42.86131738850902, 140.70182135196615 on a map.

This tool works really well. I've built a few over the years with it and you can use almost any kind of snow. Sort of like 3D printing. https://grandshelters.com/icebox-igloo-tools/

Thanks for the recommendation. It does look like a well made tool, and might work a lot better with typical non-arctic snow.

Yeah I've built with, wet, dry and new and old snow without issue. You have to pack it into the form and let it set a few minutes when it's really dry before moving the form. Takes about six hours for two people, maybe ten the first time to build an eleven foot diameter igloo.

In late January earlier this year we got about 3" (7.5 cm) of snow here in the piedmont area of NC. It only stayed below freezing for a day or two.

With that little bit of snow, a neighbor built a fake (?) igloo for their kid on their front yard. It was a pretty good size too, large enough to hold at least one adult.

What surprised me was how long it lasted. It wasn't below freezing for very long but the igloo stuck around for maybe a week even after temperatures were going above 60°F (15°C) during the day. It was in full sun during the day also.

This neighbor had previously built a sled track entirely out of snow parallel to their driveway another winter. So they are handy with snow.

Snow melts based on surface area, roughly - so an igloo will take about as long to melt as a similarly large pile of snow - and those can last quite awhile after the sun warms up.

Warm rain is what kills snow.

I wonder if you could build a pizza over similarly?

Good refractory snow is very uncommon, now-a-days; regular snow won't allow proper circulation in the oven above 300°C.

You can make your own refractory snow…just fire the inside to 800F for a second. This melts the snow on the inside which freezes instantly forming an extremely rigid layer.

Personally I would not trust a snow oven to make a regular pizza…though it could be handy to make frozen pizzas in.

The best refractory snow for pizza igloos comes from Naples.

I'm wondering if the "spiral" dome style has more use cases.

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